Abstract

BACKGROUND:

There is a great need for a simple activity assessment tool that can reliably predict activity in patients with Crohn's disease (CD).

AIM:

To investigate the relationship between serum cytokines and endoscopic activity of CD using Crohn's Disease Endoscopic Index of Severity (CDEIS) as a gold standard.

METHODS:

We prospectively evaluated 32 firmly established CD patients using ileocolonoscopy, CDEIS score, and Crohn's Disease Activity Index (CDAI) score. Blood samples for cytokine analysis were obtained 1 day prior to procedure.

RESULTS:

The correlation between CDEIS and CDAI was moderate (r = 0.43; P = 0.01); however, the correlation between CDEIS and inflammatory cytokines was excellent, with the highest coefficients for tumor necrosis factor alpha (TNFalpha) and interleukin-6 (IL-6) (r = 0.96 and r = 0.96, respectively; P < 0.001). CDEIS and anti-inflammatory cytokines were correlated nonlinearly (power function). We identified two separate models for predicting CDEIS value, based on the best performing pro-inflammatory [CDEIS = 0.445 x (IL-6) - 5,143] and anti-inflammatory [CDEIS = 27.478 x (IL-10)(-0.71)] cytokines. Both IL-6 and IL-10 models had high adjusted R(2) values (0.916 and 0.954, respectively). IL-6 had excellent diagnostic accuracy for detecting patients with CDEIS >7 (active disease), with area under the receiver operating characteristic (ROC) curve of 1.0 [95% confidence interval (CI) = 0.89-1.0; P < 0.001].

CONCLUSION:

Serum cytokine levels are excellent predictors of endoscopic activity in patients with CD.